Crude lithopone and improved method of manufacturing the same



My 15, 192s. 1,669,857

J. H. CALBECK CRUDE LITHOPONE AND IMPROVED METHOD OF MANUFACTURING THE SAME Filed Jan. 2l, 1926 Patented May l5, 1928.

wUNITED STATES PATENT OFFICE.

JOHN E. cALBEOx, OFJOPLIN, MISSOURI, AssiGNOR To THE EAGLE-PICKER LEAD COMPANY, or CINCINNATI, OHIO, A CORPORATION or OHIO.

GRUDE HTHOPONE AND IMPROVED METHOD OF MANUFACTURING THE SAME.

Application lcd January 21, 1926. Serial No., 82,660.

My invention relates tothe manufacture of lithopone and has for its object the production of a vcrude lithopone of a distinctlve character by a method which will insure that the lithopone shall at all times be precipltated under the same conditionsthat is to say, in mixtures of aqueous solutions of zinc sulphate and barium sulphide the composition and concentration of which remain approximately constant; a further objectl which I have 'in View is to bring about the precipitation of the lithopone in highly d1- luted mixed solutions of the zinc sulphate and barium sulphide and under conditions which make this economically practicable. By bringing about the precipitation of lithopone under these conditions I insure a llthopone of remarkably even quality and of which the. precipitated particles and thel pulp which they form have remarkably good qualities, as will be pointed out later.

My invention vgenerally speaking consists v in the method of precipitating lithopone in which solutions of zinc sul hate and of barium sulphide, preferably highly dilutedhare continuously run in reactive proportions into a precipitating and mixing tank in which the liquids and suspended particles of precipitate are maintained at a constant level and continuouslydrawn off, preferably through additional precipitating and mixing tanks into a tank in .which the lithopone pulp is permitted to settle and from which it is drawfof for further treatment of the usual kinds. My invention also consists in the new crude lithopone produced by my process which has distinctive qualities as compared with crude lithopone as heretofore produced.

My new method will be best' understood as further described in connection with the drawing -which is a diagrammatic chart of apparatus'lsuitable for the practice of my invention and in which A and B are, respectively, reservoir tanks for zinc sulphate and for bariumsulphide, the solutions of which may properly be of the usual density of these' solutions as usually employed in the manufacture of lithopone by the usual methods. A1 and B1 are tanks in which the solutions from tanks A and B vare diluted. `The strong solutions running out through ipes a and b and being controlled by valves and C1 so that they will flow to tanks A1 and B1 in reactive proportions., Stirrers F and F1 suspension in the tank by a stirrer F2 and the liquid contents of the tank-is maintained at a constant level running out from near the top of the tank through a conduit d.

As shown, and by preference, the conduit d delivers the liquid and suspended precipitate into another pi'ecipitating and mixing tank D1 having a stirrer F3 and an outer conduit d1 delivering the liquid and precipitate to still another precipitating and mixing tank D2 having a stirrer 'F4 and an outer conduit d2 leading to a settling tank E in.

which the lithopone particles are deposited 1n a pulp at the bottom and continuously drawn olf through conduit .C by pum H and. delivered through conduit I to filters (not shown).

'The Water flowing into' gutter E1Vat the top of tank E, together with water'soluble salts, is drawn oif through pipe J and forced by pump K through conduit J1.

Conduits aa and bb having regulatihg valves CT vand CB lead from tanks A andB into tank D1 and can be used to correct .any

error as tothe reactive proportions of the solution which may appear by analysisof the outflow from tank D. It will be obvious that the advantages incident to precipitating thelithopone under uniform conditions are secured irrespective of the strength of th barium and zinc so utions employed in the process. Marked ad'- vantages are, however, secured by carrying out, m method with solutions of considerable dilution as compared with .those heretofore employed in making lithopone by usual methods; For example, in commonly used methods itis not advisable to use barium liquors of lower concentration than 10%, barium, sulphide, or zinc liquors of lower concentration than 14% ZnSO4. In my method I find it advisable to dilute the solution so that at. the time of reaction the strength shouldl not exceed one tenth of that normally used, that 1s to say I`dilut'e the Ifus no, l

barium sulphide solutions to a concentration of not exceeding 1% BaS and the zine sulphate solutions to a concentration not exceeding 1.4% ZnSO. In preference I use a barium liquor of about 1% and a zine liquor of about 1%. The crude lithopones produced by my process, especially where the barium and zinc solutions are diluted not to exceed a concentration of 1%, has marked advantages over crude lithopones heretofore produced. Thus (l) my lithopone if the freshly precipitated pulp is flowed on a sheet of glass coats it with a uniform smooth opaque coating; (2) the pulp settles more rapidly and contains less water to be filtered out; (3) my crude -lithopone has a much higher strength and hiding power than ordinary crude lithopone and'possesses high oil absorption; (4) my lithopone requires a nia'- terially less mailling temperature to obtain maximum strength in the finished product. For example, I have found that a muiiling temperature of 9500 F. is sufficient with my product and that is about 200 F. less than is usually necessary; (5) my crude lithopone occludes less of the electrolyte used in precipitation than is found in lithopone produced by known methods, so that, for instance, three or more times as much chloride can be used as compared with known processes and yet alight prooflithopone produced- (6) the ultimate particle of lithopone formed by my process is larger, more stable and more definitely formed than is the case with crude lithopone as heretofore produced. Thus the ultimate particle in my crude lithopone will have a magnitude approximating that of a good average pigment particle, say from .5 to .85 microns, making the crude lithopone a not unsatisfactory pigment and making it possible to impart to thel product the maximum color strength and opacity by muflling the crude product at a temperature much lower than has heretofore been necessary. Thus I find that my crude lithopone made of chlorine free li uors can be brought to the maximum strengt 1 by muflling it at a temperature 200 F. below that us :ally found necessary, say at a temperature ol" about 95()o F.

Having now described my invention, what I claim new and desire to secure by Letters latent is:

-1. In the manufacture of lithopone the method of producing crude lithopone of high quality' which consists in continuously running aqueous solutions ot zine sulphate and of barium sulphide in reactive proportions into a precipitating and mixingr tank, energetically stirring the contents of said tank, continuously drawing olf the contents of said tank in such manner as to maintain an approximately constant level therein and approximately constant concentration of the liquid contents thereof and settling out a lithopone pulp from the mixture drawn from the tank.

2. In the method of elainrl the further step of continuously passing the mixture from the precipitating and mixing tank through one or more similar precipitating and mixingr tanks prior to settling out the pulp so as to insure a complete reaction.

2l. The method of claim las carried out with dilute solutions of zinc sulphate and barium sulphide of materially less than 10% concentration.

4. The method of claim 1 as carried out with dilute solutions of zinc sulphate and barium sulphide of approximately 1% concentration.

5. In the method of claim 1, the further step of continuously1 diluting concentrated solutions of zine sulphate and barium sulphide preparatory to the continuous delivery of the dilute solutions into the precipitating and mixing tank.

JOHN H. CALBECK.

c DlsoLAIMER. j I 1669g57'"]07m H'- albeck JOPII, M0. CRUDE LrTHoPoNE AND IMPROVE METHOD 0F MANUFACTURING THE SAME. Patent dated May 15, 1928. Disclaimer filed April 23, 1929, by the patentee and the assignee, The Eagle-Picker Lead Company.

Y vHereby enter this Adisclaimer to that of the claims in Said specification which is in the following Words', vto Wit:f L l 1. In the manufacture of lithopone the method ofv producing crude lithopone of high quality which consists in continuously running aqueoussolutions ofrzin'czsulphate and of barium ulphide in reactive, propo1"t`ions into a precipitating and mixing tank,

energetically stirring the contents of said tank, continuously drawing off the contenta of said tank in such manner as to maintain an approximatelyconstant levelV therein.

and approximatelycons'tant concentration of the liquid contents thereo and settling out a lithopone pulpfiomthe mixture drawn from the tank."

2. In the method? claim'xl the further step of continuousl passing the mixture from 'the precipitating miiiilgftank through one or more. similar precipitating and' mixing tanksvprlorto settling-'out the pulp vSQ as to insurefa complete reaction. [Oficial Gazette May 7^, A 1 

